Help in deciphering engine codes from 1991 Coupe

Hi, this evening my check engine light came on in my 1991 780. This happened after a few minutes of driving and a slightly harder than normal stop followed by getting up to freeway speed. The car seems to driving normal with no starting or stalling problems (so far).

Here are the codes the computer gave -

2-3-1

I used to have a 240 that had issues after the check engine light came on. The problems got progressively worse and the issue was finally traced to a bad O2 sensor after many bad diagnoses. Is anyone familiar with the 700 series who have had the same problem with the check engine light and similar codes?

thanks lp